Enhanced processing following a warning cue is thought to be mediated by a phasic alerting response involving the locus coeruleus-noradrenergic (LC-NA) system. We examined the effect of aging on phasic alerting using pupil dilation as a marker of LC-NA activity in conjunction with a novel assessment of task-evoked pupil dilation. While both young and older adults displayed behavioral and pupillary alerting effects, reflected in decreased RT and increased pupillary response under high (tone) versus low (no tone) alerting conditions, older adults displayed a weaker pupillary response that benefited more from the alerting tone. The strong association between dilation and speed displayed by older adults in both alerting conditions was reduced in young adults in the high alerting condition, suggesting that in young (but not older) adults the tone conferred relatively little behavioral benefit beyond that provided by the alerting effect elicited by the target. These findings suggest a functioning but deficient LC-NA alerting system in older adults, and help reconcile previous results concerning the effects of aging on phasic alerting.

中文翻译：

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相位警报系统功能完整性的年龄相关变化：瞳孔测量研究

警告提示后的增强处理被认为是由涉及蓝斑-去甲肾上腺素能 (LC-NA) 系统的阶段性警报反应介导的。我们使用瞳孔扩张作为 LC-NA 活动的标志，并结合对任务诱发的瞳孔扩张的新评估，研究了衰老对相位警报的影响。虽然年轻人和老年人都表现出行为和瞳孔警报效应，反映在高（音）与低（无音）警报条件下 RT 降低和瞳孔反应增加，但老年人表现出较弱的瞳孔反应，这从警报音中获益更多。老年人在两种警戒状态下表现出的扩张和速度之间的强关联在处于高警戒状态的年轻人中有所降低，表明在年轻人（但不是老年人）中，除了目标引起的警觉效应所提供的好处之外，语气赋予的行为益处相对较小。这些发现表明老年人的 LC-NA 警报系统功能正常但有缺陷，并有助于协调先前关于衰老对阶段性警报影响的结果。